PURPOSE: To improve the reliability of a joined part by fitting tubular joint parts by placing a metallic member whose hardness is low to the inside, placing an electromagnetic coil in the inside of these joint parts and allowing a pulsative large current to flow, and welding by pressure and joining each of both the joint parts.
CONSTITUTION: Metallic members 1, 2 having a tubular joint part 1c are joined mutually in its joint part. As for said both metallic members, those which have different hardness are used, and said both tube joint parts are fitted to each other so that the metallic member whose hardness is low become the inside. By placing an electromagnetic coil 3 in the inside of these joint parts and allowing a pulsative large current to flow to this coil, both the joint parts are welded by pressure and joined mutually. In such a way, it is possible to join them in any position, and also, a brazing failure which follows a flux entrapment phenomenon is not generated either, and also, troublesome dew-point management and temperature management, etc., become unnecessary.